INSECUTOR INSCITI^ MENSTRUUS 3 



Yukon Valley. — The river rises in a series of great lakes 

 which lie to the eastward of the coastal barrier mountains. 

 These great reservoirs prevent sudden floods and there is no 

 flood-pool fauna. The country is forested with spruce and 

 pine, though rather sparsely and openly. Semi-prairie condi- 

 tions are produced, of which prodotes and callithotrys, a new 

 form allied to campestris D. & K., take advantage, flying abun- 

 dantly in the open. The latter species seems confined to the 

 pine country, as I met with it only in the vicinity of White 

 Horse, with what may have been a stray specimen at Skagway. 

 All the other species of the Canadian fauna are represented 

 except intrudens and diantaeus, and there is a form represent- 

 ing the eastern stimulatis Walker in river pools, which I de- 

 scribe as new on account of certain small differences. The 

 dominant species is lasarensis, frequenting the forest. The 

 three Rocky Mountain species of CuUseta are common along 

 the Yukon, and there is one rare Anopheles, but no Culex. 

 The Yukon fauna crosses the White Pass and reaches tide 

 water at Skagway, Alaska. 



The swarming habits of the common males at White Horse 

 were constant and interesting. The town is in the sandy level 

 river-fiat with a high bluff behind, formerly the river margin. 

 On walking toward the bluff any still evening, males were en- 

 countered, first the callithotrys in the tops of the small pines ; 

 next prodotes over open spaces between pines and willows, 

 then, on reaching the high spruce trees, lazarensis, high up 

 opposite the ends of projecting branches, and lastly in open- 

 ings between tall spruce, over willow bushes, punctor, and an 

 occasional excriicians, high up and flying wildly. At Dawson, 

 pidlatus appeared over willow bushes on the hillside any time 

 after 4 p. m. that the sun went behind a cloud. 



I note the following desiderata for the Canadian fauna : 

 Larvae of callithotrys Dyar ; mating habits of intrudens Dyar. 



Aedes punctor Kirby. 



Culex punctor Kirby, Richardson's Fauna Bor. Am., iv, 309, 1837. 

 Culex implacabilis Walker, List Dipt. Brit. Mus., i, 7, 1848. 

 Culex provocans Walker, List Dipt. Brit. Mus., i, 7, 1848. 



